2. Need for Culture Media
โข Medium
โข Nutrient
โข Support growth
Bacteria mixed population in nature
By appropriate procedures they have to be
grown separately (isolated) on culture media
and obtained as pure culture study
Liquid medium Two type of culture medium Solid medium
3. Liquid & Solid Medium
โข Liquid Medium
Diffused growth
No characteristics for identification
Difficult to isolate
โข Solid Medium
Distinct colony morphology
Characteristics___ easy to identify
Colony___ microscopically visible collection of millions of bacteria originating
from a single bacteria cell
4. Types of Culture Media
โข Simple Medium
โข Complex Medium
โข Synthetic Medium
โข Special Medium(Enriched Media, Enrichment Media, Selective
Media, Indicator Media, Differential Media, Sugar Media)
โข Based on oxygen requirement
Aerobic Media
Anaerobic Media
5. Types of Culture Media
โข Simple Media
(Most common in routine tests, e.g. Nutrient Broth, Nutrient Agar)
Consists of peptone, Meat extract, NaCl, Water, 0.5% Glucose, 2% Agar
โข Complex Media
They have added complex ingredients such as yeast extract, casein
hydrolysate provide special nutrients
โข Synthetic Media
Media prepaid from pure chemical substances
Used for special studies e.g. metabolic requirements
e.g. peptone water (1% peptone+0.5% NaCl in water)
6. Types of Culture Media
โข Enriched Media
Substances like blood, serum, egg are added to the basal medium.
Used to grow bacteria that are exacting in their nutritional needs e.g. Blood Agar
Chocolate Agar.
โข Enrichment Media
Liquid media used to isolate pathogens from a mixed culture.
Inhibit growth of unwanted bacterium increase in numbers of desired bacteria
โข Selective Media
The inhibitory substances is added to a solid media
Increase in number of colonies of desired bacterium
e.g. Mac Conkeyโs Medium ( for gram negative bacteria)
Lj Medium ( for M.tuberculosis)
7. Types of Culture Media
โข Indicator Media
Contain an indicator which changes
its color when a bacterium grows in them
โข Differential Media
Distinguish between lactose fermenters
and non lactose fermenters bacteria's e.g. Mac Conkeyโs Medium
โข Sugar Media
Media containing any fermentable substances
e.g. glucose, arabinose, lactose, starch etc
1% of the sugar in peptone water+ indicator
Contain a small tube(Durhamโs tube) for the detection of gas by the bacteria
8. Types of Culture Media
โข Anaerobic bacteria
These bacteria are used to grow anaerobic organisms.
Culture Methods include:
Streak culture
Lawn culture
stroke culture
Stab culture
Pour plate method
Liquid culture
Anaerobic culture methods
